Recent rain may bring welcome grass growth after a dry period, but it can also change livestock disease risks quickly.
Farmers in England and Wales should monitor stock closely and review parasite, nutrition and vaccination plans with their vet.
See our action checklist for farmers for advice on the daily checks to be completed with animals, as well as how to review and when to report animals with your vet and the authorities.
Parasite challenge may rise quickly
Rain softens and breaks up dung pats, allowing worm larvae to move onto surrounding herbage. Moist conditions also help larvae survive and travel up grass stems, where they can be eaten by grazing animals.
The greatest immediate concern is often youngstock, particularly lambs and first-season grazing cattle with limited immunity.
Watch lambs for poor growth, loss of condition, diarrhoea and pale eyelids or gums. Haemonchus contortus, or barber’s pole worm, can cause severe anaemia and death without diarrhoea.
Regular faecal egg counts, liveweight monitoring and careful observation should guide treatment decisions.
Remember that egg counts may take two to three weeks to rise after larvae are eaten, so do not ignore declining growth rates or changes in appearance while waiting for laboratory results.
In cattle, coughing or breathing difficulty at grass should raise suspicion of lungworm, especially in first-season grazers, although older animals can also be affected. Wet, mild conditions and high pasture contamination increase risk.
Seek veterinary advice promptly because severely affected cattle may deteriorate rapidly and can require supportive treatment as well as an appropriate anthelmintic.
Think ahead about liver fluke
A short period of rain does not mean immediate liver fluke disease everywhere. However, warm, wet conditions favour the mud snail needed for the fluke lifecycle, particularly around springs, ditches, poached gateways and poorly drained ground.
Risk varies substantially between farms and even between fields, so use local forecasts, grazing history and diagnostic testing rather than treating solely by the calendar.
Rapid grass growth brings metabolic risks
Fresh grass following rain may be high in moisture and potassium, which can reduce magnesium absorption. Recently calved cows, lactating ewes and animals under nutritional stress may therefore be vulnerable to hypomagnesaemia.
Early signs include nervousness, ear twitching, muscle tremors and reduced milk yield, progressing to staggering, collapse, convulsions or sudden death.
Review magnesium supplementation and grazing arrangements with your vet or nutrition adviser.
Bluetongue remains a priority
Rain does not remove the bluetongue threat. Warm late-summer conditions can support midge activity, and cases of BTV-3 are continuing in England and Wales.
Check sheep and cattle for fever, mouth lesions, drooling, facial swelling, lameness, nasal discharge, falling milk yield and abortions. Discuss vaccination and the health status of purchased animals with your vet.
Bluetongue is notifiable, so report suspicion immediately.
Act now: check stock daily, monitor growth and body condition, investigate coughing or sudden deaths promptly, sample before worming where appropriate, and adapt the farm health plan to current field conditions.
More on bluetongue
The realities of bluetongue – NFU Dairy Board Chair on facing BTV-3 on farm
Bluetongue – act now, before the virus reaches your farm
Caring for animals with suspected or confirmed bluetongue
Bluetongue – vaccination best form of defence as concern grows over spread of virus
Watch again: NFU bluetongue webinar – latest situation and practical steps from experts
Bluetongue vaccination – protecting fertility, stock and farm businesses
Action checklist for farmers
Daily checks with animals
Check cattle and sheep at least daily, paying particular attention to lambs, first-season grazing cattle and recently calved or lactating animals.
- Monitor growth, body condition and dung consistency. Use liveweight records and faecal egg counts to support parasite treatment decisions, rather than relying on routine blanket worming.
- Look for pale eyelids or gums in sheep, which may indicate anaemia caused by Haemonchus, even when diarrhoea is absent.
- Investigate coughing or breathing difficulty in cattle promptly, particularly in youngstock at grass, as lungworm can progress rapidly.
- Review liver fluke risk field by field, focusing on wet, muddy or poorly drained areas around ditches, springs and gateways. Base treatment on risk assessment and diagnostic evidence.
- Review magnesium provision for recently calved cows, lactating ewes and other vulnerable stock when grass begins growing rapidly after rain.
- Remain alert for bluetongue signs, including fever, mouth lesions, drooling, facial swelling, lameness, nasal discharge, reduced milk yield and abortions.
Work with your vet and authorities
- Check the health and bluetongue status of purchased animals, and discuss vaccination with your vet before buying or moving stock.
- Report suspected bluetongue immediately to APHA (Animal and Plant Health Agency). In England, call 03000 200 301; in Wales, call 0300 303 8268.
- Investigate sudden illness or unexplained deaths quickly, and contact your vet before moving the animal or carcase.
- Update the farm health plan with your vet, reflecting current grazing conditions, recent rainfall and risks specific to individual fields.
